A multinuclear NMR approach has been used to elucidate the structural and dynamic properties of complex biomolecules. 31P NMR Studies of phosphate complexes of native, apo and metal-ion-substituted alkaline phosphatases have permitted direct determination of the stoichiometry of complex formation and assessment of the environment experienced by the phosphorous bound at the active center and implicated in the mechanism of action of this enzyme. Further, these studies have provided compelling evidence for the existence of cooperative interaction affecting ligand binding between the subunits of this dimeric enzyme. 31P chemical shifts and spin-lattice relaxation studies of deoxyoligonucleotides have provided information relating to the conformational transitions of these systems and their motional properties in solution. 1H, 19F and 31P NMR studies of gene 5 protein from bacteriophage fd and its complexes with tetra and octanucleotides have provided sufficient detailed structural information to permit the construction of a 3 dimensional model of the gene 5-nucleotide complex. 31P NMR analysis of glycophorin A, the major human erythrocyte sialoglycoprotein, has identified the phosphorous associated with this protein as arising from diphosphoinositide. All the diphosphoinositide is associated with the hydrophobic region of the protein suggesting that there is a specific affinity between this phospholipid and the intramembranous portion of glycophorin A. NMR studies of 113Cd (II) substituted for the native metal ion in a variety of metalloenzymes have allowed direct observation of the metal ion, essential in promoting catalytic activity, in the microenvironment of the protein. The NMR parameters of the enzyme-bond 113Cd (II) in carbonic anhydrases and alkaline phosphatase appear to be related to the pH activity profiles of these enzymes, thereby reflecting functionally critical changes occuring at the active site.